Electrical contact member



1943. w. J. KNOCHEL ET AL 2,332,090

ELECTRICAL CONTACT MEMBER Filed March 6, 1942 WW AI IORNEY Patented Oct.19, 1943 UNITED STATES PATENT OFFICE ELECTRICAL CONTACT MEMBER VaniaApplication March 6, 1942, Serial No. 433,560

1 Claim.

This invention relates to electrical contact members, and particularlyto a member which is subjected to heat in manufacture and for use, suchas contact prongs of an electronic device.

Copper is a most popular material for use in conducting electricity orfor making connection between conductors. While copper is an excellentconductor, copper oxide is a poor conductor. Copper oxide forms readilyon copper, especially when the copper is heated. Contact members ofcopper which are subject to heat either while in process of manufactureor attachment or while in use, have to be cleaned to remove the copperoxide. The time and difliculty involved in that operation, as well asthe wearing-away of the member, represent material losses.

An object of the present invention is to prevent the losses abovementioned encountered in construction and use of contact members.

Another object of the present invention is to provide a structurewherein the contact memher is maintained inherently in good conductingcondition on its contact surface.

A further object is to prevent formation of a non-conductive or highlyresistant oxide, particularly copper oxide on a contact member contactsurface.

Still further objects of the invention will appear as the descriptionprogresses both by direct statement thereof and by implication from thecontext.

Referring to the accompanying drawing in which like numerals ofreference indicate similar parts throughout the several views;

' Figure l is a sectional view of our invention in connection with anelectronic device a portion of the envelope for which is also shown insection; and

Figure 2 is a cross-section on line 11-11 of Fig. 1.

In the specific embodiment of the invention illustrated in said drawing,the reference numeral Ill designates a glass or other envelope of anelectronic device. Where electric lead-in connection is to be made, theenvelope is provided with a reduced neck II at the outer end rim ofwhich is sealed therein a peripheral marginal end I! of a thimble l3.This thimble constitutes the specific illustration here selected asexemplary of our improved contact member and with associated metallicparts is commonly termed an attaching prong. Within the thimble is ametallic pin l4 of suitable material and configuration and preferably ofa size to fill the outermost and diametrically reduced end portion I5 ofthe thimble. Suitable solder or other means 16 is shown physically andelectrically joining the pin and thimble.

It is the outside surface of the said reduced end portion which isexposed to the atmosphere which has been troublesome to maintain cleanfor electrical contact purposes. Inasmuch as the said thimble is made ofcopper, and as copper readily oxidizes during sealing, exhaust, test andlife of the electronic device, and copper oxide is an exceedingly poorconductor both of electricity and heat, its presence is highlydetrimental. Heretofore much time, effort and material have beenconsumed in cleaning the oxide from the copper surface, not only at timeof manufacture but frequently during use of the device.

According to the present invention, the exterior of the reduced portionof the thimble is covered with a conductive material. If that materialis one on which an oxide or other readily forming coating will result inmanufacture or use, selection is made of a material of which thecompound will be adequately conductive. By preference, we use a noblemetal such as silver or gold to form a closely fitting shell or coatingil. Specifically, the preferred material and method is silver, platedupon the thimble electrically or otherwise. Even though this silverplate is subjected to a high temperature and forms an oxide, its oxideis not objectionable since silver oxide has high electrical and heatconductivity. Consequently the silver plated thimble, whether thecoating remains on its surface as silver or as silver oxide, issatisfactory for electrical and heat conductivity and overcomes theformation and presence of copper oxide on the contacting surface.

We claim:

In combination with an evacuated envelope, a solid metallic pin withinsaid envelope and subject to the vacuum therein, a copper thimble sealedto said envelope and also subject at its interior to the vacuum of theenvelope and thereby kept from oxidizing on its interior surface, saidthimble having a diametrically reduced portion and said pin havingsurface contact with the interior of the reduced portion of said thimbleand the contacting surfaces prevented from oxidizing by presence of thevacuum, and a coating of noble metal on the entire exterior surface ofthe reduced portion of said thimble for preventing formation of copperoxide thereon and for obtaining unimpaired electrical connection to anypart of the reduced portion and from the outer surface of said coatingto the said pin.

WILLIAM J. KNOCHEL. SIDNEY JOHN CHERRY.

